Montreal is about 4.8 times bigger than Fort Lauderdale.

Fort Lauderdale (excluding the city's 9.9 sq km of water area) is approximately 90 sq km, while Montreal is approximately 432 sq km, making Montreal 379% larger than Fort Lauderdale.
Tip: This to-scale comparison of Fort Lauderdale vs. Montreal uses the Mercator projection, which distorts the size of regions near the poles.